Liquid reagent cartridge cuvette

ABSTRACT

This application discloses a liquid reagent cuvette cartridge which is adapted for use with an analyzer apparatus. The disposable, substantially rigid cartridge includes a chamber and a plurality of cuvettes disposed adjacent the chamber. The cartridge has no secondary air escape means. An opening is located between the chamber and each cuvette. The cartridge is preferably filled by a series of pressurizing steps in which pressure is exerted on fluid in the chamber and fluid from the chamber is forced into the cuvettes. The air pressure in the cuvettes and chamber is then equalized, after which the chamber is again pressurized and fluid is again forced into the cuvettes. The filling operation is repeated until the cuvettes are uniformly filled to the desired level. The cuvette filling operation occurs in essentially a closed system so that the air in the cuvettes is not permitted to escape during a filling operation.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part of my previously filedpending application Ser. No. 876,079 filed Feb. 8, 1978.

BACKGROUND OF THE INVENTION

The present invention relates generally to a new and improved cuvettecartridge for use with a chemical and microbiological analysis apparatusand to a method of transferring biological or other fluid from a growthor filling chamber in the cartridge to a plurality of cuvettes.

Biological fluid analyzer apparatus, such as disclosed in U.S. Pat. Nos.Re. 28,800 and 3,718,439, are capable of performing antibioticsusceptibility testing, medical bacteriology procedures, clinicalchemical analysis and other related procedures. When an evaluation isundertaken with this apparatus, a biological fluid to be evaluated suchas serum, plasma, urine, cerebrospinal fluid is inoculated into anartificially prepared nutrient of reagent fluid and placed into acuvette cartridge of the type disclosed and claimed in Acker et al.,U.S. Pat. No. 4,013,368. The prior art cartridge includes a growthchamber and a plurality of cuvettes disposed below the chamber. Fluidcommunication means are provided between the chamber and cuvettes toallow fluid to be transferred from the chamber to each of the cuvettes.

In addition to receiving the fluid to be analyzed, the cuvettes areadapted to accommodate liquid reagents which are intended to interactwith the contents of the fluid to be analyzed. In the preferredembodiment, the liquid reagent will contain an antibiotic which may ormay not be effective to retard the growth of bacteria transfered to thecuvettes from the growth chamber according to this disclosure. Oneapplication of the claimed device envisions introducing blood samplesinto the cuvettes, transferring the bacteria from the growth chamber tothe cuvettes and determining whether there is sufficient antibioticactivity in the blood sample to effect the growth of the bacteria.

Once the fluid is transferred into the cuvettes, the antibiotic reagentforms an antibiotic and media/microorganism suspension. The bacterialgrowth rate for the fluid in the various cuvettes can then be monitoredby means of a plurality of individual optical detector systems, each ofwhich is in registration with its respective cuvette.

Electronic computation means such as computers and/or other computingdevices well known in the art, are available to evaluate the output ofthe detection system and to make appropriate calculations, eitherthrough analog or digital means, to record and display the results in ameaningful and appropriate manner. These results include, for example,the changes in the growth rate in each cuvette and the relative changesbetween the control cuvette containing no antibiotic and the samplecuvettes.

Unfortunately, cuvette cartridges presently employed with fluid analyzerapparatus available in the art are not entirely satisfactory for anumber of reasons. Initially, cuvette cartridges presently known in theart are costly due to their particular physical structures, therelatively complex manufacturing procedures associated with making thecartridges and the quality control procedures required to assure thedesired cartridge quality. These factors are all significant when it isconsidered that the cartridge is a disposable type device generallyassociated with a one time use.

For example, one cuvette cartridge known in the art and disclosed inU.S. Pat. No. 4,013,368 utilizes a resilient unidirectional valve and agas permeable tubular member as part of its system for transportingfluid from a growth chamber to a plurality of cuvettes. This particularstructure has not been entirely satisfactory because of the expenseassociated with the materials utilized to make the cartridge and becausethe gas permeable member is not always uniform in its structuralcharacteristics along its length, a drawback which not only adverselyaffects gas removal from the system but also requires increased qualitycontrol procedures.

Another cuvette cartridge which is known in the art is a membrane typecuvette cartridge. In this particular embodiment, a chamber, locatedabove the cuvettes, is partitioned to form two compartments. Onecompartment serves as a fluid growth chamber while the remainingcompartment serves as a vacuum compartment. A partition, which separatesthe upper chamber compartments from the lower cuvettes, has openingswhich serve as passages for biological fluid being evaluated and for gaswhich is evacuated from the cuvettes. A hydrophobic membrane strip isaffixed to the top surface of the separating partition so that it coversthe various openings in the bottom wall of one chamber compartment and ahydrophobic membrane strip also is affixed to the bottom wall in theremaining chamber compartment. In operation, air in the cuvette isevacuated from the cuvette into the vacuum compartment while the fluidis forced through the hydrophobic membrane strip into each of thecuvettes.

Problems, aside from manufacturing and quality control problems, existwith the membrane type cuvette cartridge. The membrane type cuvettecartridges presently available have been designed to substantially fillthe cuvettes with fluid. However, various applications require that airbe present in the cuvettes, inasmuch as aerobic bacteria require oxygenfor growth. Efforts to provide uniform air bubbles in the cuvettes ofthe membrane type cuvette cartridge have been unsuccessful. Because ofthe particular physical characteristics of the membrane at the locationof the opening to each cuvette, the air flow through the membrane intoeach of the cuvettes varies substantially. As a result air will flowinto one cuvette easier than it will flow into another cuvette due tothe impedance caused by the structure of the membrane strip. Thedifference in impedance of the membrane at the various openings to eachof the cuvettes causes non-uniform air bubbles in the cuvettes.

Another disadvantage that sometimes occurs with the utilization of themembrane strip is that the fluid located in the interstices of themembrane strip creates a hydraulic lock so that air cannot pass into thecuvettes. As a result, the bacteria in the fluid located in the cuvettesis starved of oxygen, thereby adversely affecting bacterial growth inthe cuvette.

What is desired is a cuvette cartridge in which the individual cuvettescan be filled without the cost, assembly and quality control problemsassociated with cartridges presently available. Moreover, it is desiredto have a cuvette cartridge in which the cuvettes are not completelyfilled, but instead have a relatively uniform amount of air available ineach cuvette to permit proper growth of the bacteria in the cuvettes.

SUMMARY OF THE INVENTION

The invention disclosed and claimed herein serves to eliminate theproblems associated with cuvette cartridges presently available. Thecuvette cartridge of the present invention provides for a closed systemin that there is no secondary air escape means. Therefore, the cuvettescan be partially and relatively uniformly filled so that air isavailable in the cuvettes to allow for proper growth of the bacterialfluid when it is located in the cuvettes. Moreover, the cartridge of thepresent invention can be readily made without the cost, manufacturingand quality control problems attendant with the membrane andunidirectional valve type cuvette cartridges.

Briefly, the cuvette cartridge of the present invention is adapted foruse with analyzer apparatus presently available and disclosed, forexample, in U.S. Pat. No. Re. 28,800. The cartridge preferably ismembraneless, and the growth chamber need not be compartmentalized.While a number of embodiments can be utilized, one embodiment includes acartridge comprising a growth chamber which is coextensive with anddisposed above a plurality of cuvettes. The bottom wall of the growthchamber serves as the top wall for the cuvettes. An opening is locatedin this wall above each of the cuvettes. First members extend upwardlyfrom this wall into the chamber at the location of each of the spacedopenings. The first members are of a length which is less than theheight of the growth chamber. Second members, which are slightly largerin internal diameter than the external diameter of the first members,extend downwardly from the roof or lid of the cartridge but stop shortof the growth chamber floor. Each of the second members is axiallyaligned with and partially overlaps a respective first member to definea separate, annular, column-like passageway between the chamber and eachcuvette.

In use, each cuvette is loaded with a liquid antibiotic reagentintroduced through a port means located at the bottom of each cuvetteand sealed with a plug. The upper growth chamber is filled with aparticular fluid media through a filling port located in the lid or roofof the cartridge. Once the desired amount of fluid is placed in thegrowth chamber the filling port is closed with a plug having a gaspermeable, liquid and bacteria impermeable membrane through which airmay pass. Preferably, the chamber is then suitably pressurized, with gasintroduced through the membrane. The fluid media being incompressiblewill be forced up the various annular passageways formed by the firstand second overlapped members where it will spill over the upwardlyextending first members and pass downwardly therein and through theopenings in the bottom wall of the growth chamber into the individualcuvettes, whereupon the individual cuvettes are filled with fluid. Thefluid flow will continue until the pressure in the cuvettes hasincreased or equalized itself to the pressure in the upper growthchamber pursuant to Boyle's law relating to gases, i.e., P₁ V₁ /T₁ = P₂V₂ T₂. Thus, when the gas pressure P₁ is increased to P₂, the volume ofthe gas will increase from an initial volume V₁ to a higher gas volumeV₂ in the upper chamber while the reverse is occurring in the cuvetteswhich are being filled with fluid.

The cartridge of the present invention can be readily manufactured withthe first and second members being integrally formed as part of thechamber roof and bottom wall, respectively. The quality control andassembly problems associated with the membrane style cartridge areobviated.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention together with its further objects and advantages thereofmay be best understood by reference to the following description takenin conjunction with the accompanying drawings, in which like referencenumerals identify like elements in the several figures and in which:

FIG. 1 shows a perspective view of the cuvette cartridge of the presentembodiment;

FIG. 2 shows a top view of the cuvette cartridge of FIG. 1;

FIG. 3 shows a side view of the cuvette cartridge partiallycross-sectioned to show tubular members, dams and half caps;

FIG. 4 shows an enlarged partial sectional view of the cuvette cartridgetaken along line 4--4 in FIG. 2;

FIG. 5 shows an inverted partial end sectional view taken along line5--5 in FIG. 4;

FIG. 6 shows an inverted partial end sectional view taken along line6--6 in FIG. 4;

FIG. 7 shows a partial sectional view taken along line 7--7 in FIG. 6;

FIG. 8 shows a reduced scale partial sectional view taken along lines8--8 in FIG. 5;

FIG. 9 shows a side portion partially sectioned to show the curved damembodiment;

FIG. 10 shows a sectional view taken along line 10--10 in FIG. 9 to showcurved dams in alternating directions.

DETAILED DESCRIPTION

Referring to the drawings, the disposable cuvette cartridge 10 of thepresent invention includes a growth chamber 11 which is positionedadjacently above and coextensive with a plurality of cuvettes 12.

Cartridge 10 includes spaced end walls 13, 14 which are joined to therespective ends of spaced side walls 15, 16. The bottom portion 18 ofsidewall 16 is recessed inwardly at 17 as shown in FIGS. 1 and 5 inorder that the cartridge can be inserted into an analyzer apparatus. Itis appreciated that the cartridge could have other physicalconfigurations in order to fit with particular analyzer apparatus. Thedisposable cartridge further includes a bottom wall 8 and a top wall orlid 19. Gussett 2 serves to strengthen the cartridge at the end of thecartridge which extends beyond the cuvettes 12. Handle assembly 6includes projections 4, which extend outwardly from endwall 13. Crossmember 5 is joined to projections 4. When a cartridge is inserted in ananalyzer apparatus, it can be picked up by handle assembly 6 and readilyinserted into the cartridge receiving opening in an analyzer apparatus.

The cartridge can be manufactured from any suitable material includingglass or a polymeric material such as a polyolefin, a polycarbonate oran acrylic. However, the material selected should provide a transparentcartridge having excellent chemical resistance properties and asatisfactory optical density for the particular application.

The cartridge can be made with lid 19 and bottom wall 8 moldedseparately from the remainder of the cartridge, after which thecartridge parts can be heat sealed together or otherwise joined in anysuitable manner to form a leak-free, air tight cartridge.

Intermediate bottom wall 8 and lid 19 is a third wall 21. Wall 21includes top surface 22 and bottom surface 23. Wall 21 is joined alongits periphery to sidwalls 15, 16 and end walls 13, 14. A plurality ofspaced openings 24 are located along the length of the wall 21. Theopenings serve as the exit for fluid from growth chamber 11 and theentrance for fluid into each cuvette 12.

Referring to FIGS. 1, 4 and 5, it will be seen that chamber 11 islocated above wall 21 while a plurality of cuvettes 12 are located belowwall 21. The cuvettes are separated from one another by means of spacedvertical walls 25 which extend from the bottom surface 23 of wall 21 tobottom wall 8. The cuvettes are positioned along the length of cartridge10 so that at least one opening 24 is located above each cuvette 12.

A first short tubular member 26 is located at each opening 24 andextends upwardly from wall 21 for a portion of the height of chamber 11as seen in FIG. 5. The outer surface of member 26 is tapered upwardlywith the smallest external diameter being located at the top of thetube. Conversely, the internal surface 27 of member 26 is tapereddownwardly with the largest internal diameter being located at the topof tubular member 26 while the smallest internal diameter is located atthe bottom of tubular member 26, at opening 24.

A plurality of second tubular members 28 are joined to and depend fromlid 19. Tubular members 28 are internally tapered at 29 to correspond tothe tapered external wall of members 26 and have a length which is lessthan the height of chamber 11. They are positioned on lid 19 so thatwhen lid 19 is placed on cartridge 10, tubular members 28 overlap andfit concentrically over first tubular members 26. Tubular member 28 hasa larger internal diameter than the external diameter of tubular member26 so that an annular fluid passageway 30 is formed between theoverlapped tubular members 26, 28.

Accordingly, when an innoculated fluid or medium is passed from chamber11 to cuvettes 12, the fluid initially travels up the annular column 30formed by tubular members 26 and 28. The fluid then passes downwardlyinside tubular members 26 and exits from chamber 11 through openings 24and into cuvettes 12.

Tubular members 26, 28 preferably are positioned in a staggered oroffset relationship to one another along the length of cartridge 10. Thestaggered alignment allows for more uniform mixing of the fluid growthmedium in chamber 11 when the cartridge is agitated in the instrument orapparatus prior to analysis.

Referring to FIG. 4, cartridge lid 19 has an opening 50 formed in lid 19for introducing an innoculated liquid medium to be evaluated. Spacedspherical members or bosses 49 project outwardly from the tapered wall48 which forms opening 50. While only two members are shown, it isappreciated that the number of projections can vary. When chamber 11 isto be filled with fluid, the end of a pipette holding the fluid can beplaced in opening 50 and seated against spherical members 9. Fluid canthen be let into chamber 11 and air in the chamber will be evacuated outopening 50 in the annular space formed by wall 48 and the external wallof the pipette.

Once the innoculated fluid has been placed in growth chamber 11, opening50 can be closed by inserting therein a press fit type plug 47 or othersuitable closure means to prevent fluid in chamber 11 from leaking orotherwise passing out of the opening. As seen more clearly in FIG. 4,plug 47 includes a small opening 46 and a gas permeable, liquid andbacteria impermeable membrane 45 disposed below opening 46. Preferably,membrane 45 is seated in a flanged recess 44 of plug 47. It isappreciated that other plug embodiments can be employed to close theopening 50.

In some applications, it is desired to make optical measurements of thefluid in growth chamber 11. However, the circular shapes of the tubularmembers 26, 28 do not provide the best optical surfaces. Therefore, tofacilitate optical measurements, one or more pairs of mating tubularmembers 26 and 28 may be molded to provide a series of flat opticalsurfaces, as shown in FIGS. 6 and 7. Specifically, member 26 is moldedto provide flat surface portions 51, 52 on internal wall surface 27 andflat surface portions 53, 54 on the outer wall surface 7 of member 26.Additionally, flat surface portions 55, 56 are molded on the internalsurface 29 of tubular member 28 and flat surface portions 57,58 aremolded on the outer surface of member 28. The flat surface portions51-58 on members 26 and 28 are molded so that they will all be alignedwhen member 28 is overlapped with member 26 as seen in FIGS. 4-6. Theflat surface portion on each tubular member are of a sufficient lengthto allow the surfaces to overlap with each other to provide the desiredoptical characteristics.

The cuvettes 12 provide the unitary chambers where the reaction betweenthe bacteria from the growth chamber will confront a particular reagentwhich has been introduced into the cuvette through a cuvette portal 78.The reagent can be in the form of a blood or serum sample containing aknown or unknown level of antibiotic activity.

Since liquid sample containing an antibiotic will be placed into thecuvette while the cuvette cartridge 10 is inverted, it is desirable toprovide a baffle means in each cuvette to prevent the sample fromentering the tubular members 26 through the openings 24. Accordingly,one embodiment of the cuvette cartridge features a series of dams 75,running longitudinally along the bottom surface 23 of wall 21. Thesedams 75 may be rectangular and flat as shown in FIGS. 4, 5 and 6 or theymay be curved as depicted in FIGS. 9, 10, 11 and 12. As indicated, thepurpose of the dams is to prevent fluid reagent introduced into thecuvettes 12 through the cuvette portal 78 from entering openings 24.

To direct the deposition of liquid reagent e.g., blood sample or seruminto the area of the cuvette separated by said dams 75 from the openings24, the cuvette portal 78 can be fitted with a half cap 76. To be mosteffective, the half cap should be situated directly opposite theopenings 24. The half cap 76 will deflect a syringe of pipettedelivering a liquid reagent into an area of the cuvette away from saidopenings 24. The dams 75 whether flat or curved will also serve toprevent the liquid reagent from entering said openings.

Once deposited within the cuvettes, the cuvette portals 78 can be closedwith a press fit plug 77 and the cuvette cartridge can be turnedright-side-up and utilized according to this disclosure.

OPERATION

In operation, a measured or desired amount of innoculated medium to beevaluated is placed in growth chamber 11 through opening 50. Plug 47 isthen pressed in position to seal opening 50. The cartridge is insertedin an analyzer apparatus such as disclosed in Acker U.S. Pat. No. Re.28,800, where it is innoculated and heated to increase the pressure inthe cuvettes, thus serving to preclude premature transfer of the fluidfrom the growth chamber to the cuvettes.

A pressure source is attached to the cartridge at plug 47. Chamber 11 isthen pressurized by a gas such as air which passes through gas permeablemembrane 45. The increased gas pressure forces the fluid in chamber 11up annular columns 30 and then down through tubular members 26. Thefluid exits from chamber 11 through openings 24 and into cuvettes 12.

The pressure normally available in the system, is not sufficient totransfer all the fluid from chamber 11 into cuvettes 12 in one cycle oroperation. Accordingly, it is necessary to transfer the fluid fromchamber 11 to cuvettes 12 in a series of pressurizing cycles until thedesired volume of fluid has been obtained in each of the cuvettes 12.

The pressure normally available in the system, is not sufficient totransfer all the fluid from chamber 11 into cuvettes 12 in one cycle oroperation. Accordingly, it is necessary to transfer the fluid fromchamber 11 to cuvettes 12 in a series of pressurizing cycles until thedesired volume of fluid has been obtained in each of the cuvettes 12.

As the pressure is increased in the growth chamber during a pressurizingcycle, the fluid in chamber 11, being incompressible, flows through theopenings 24 to the various cuvettes until the pressure in the cuvetteshas increased or equalized itself to the pressure in the upper chamber.Accordingly, when the gas pressure P₁ is increased to P₂ in the growthchamber, the volume of the gas in chamber 11 will increase as the fluidis forced into the ventless cuvettes 12. Similarly, as the volume isreduced in cuvettes 12 as fluid enters the cuvettes, the gas pressure inthe ventless cuvettes increases until equilibrium of pressure existsthroughout the cartridge.

The cuvettes are filled to the desired volume for the particularapplication. There must be a sufficient and uniform quantity of fluid ineach of the cuvettes to permit the micro-organism evaluation.

The utilization of the cartridge of the present invention with itsclosed system for retaining air in the cuvettes also serves to providean air lock, whereby fluid in the cuvettes will not travel or return tothe growth chamber in the event the cartridge is inadvertently tipped orjostled. Inasmuch as the gas pressure in the cartridge is constant afterthe cuvette filling operation, the fluid is unable to return to growthchamber 11 because the air in the system after a filling operation willnot be displaced.

If desired, a vacuum source can be applied to the cartridge after it isplaced in the analyzer machine. The vacuum causes air to exit fromcuvettes 12 to chamber 11 and fluid is pulled into the various cuvettes.The vacuum source may be located within the analyzer apparatus.

While one embodiment of the cuvette cartridge of the present inventionhas been shown, it is appreciated that it would be obvious to oneskilled in the art to modify the cartridge. What is important is thatthe cartridge be closed in that no secondary air escape means arepresent so that air escapes from the cartridge during a pressurizingcuvette filling operation. Moreover, the exit openings in the growthchamber, for the transfer of biological fluid from growth chamber 11 tocuvettes 12, should be below or at the same elevation as the final fluidlevel in the growth chamber and the entry openings in the cuvettesshould be located above the final fluid level in cuvettes 12.Accordingly, it is contemplated that the cartridge could have thecuvettes located on top of the growth chamber with concentricallyfitting members 26 and 28 being replaced by a single tubular member openat both ends and molded to wall 21. One tube would be utilized with eachcuvette. The tube would be open throughout its length and would projectdownwardly to just above the floor of the growth chamber and upward tojust below the ceiling of the cuvette. This would provide a cartridge inwhich the exit in the growth chamber was below or at the same elevationas the final fluid level in the growth chamber and in which the entryopening in the cuvettes would be above the height of the final fluidlevel in the cuvettes.

The foregoing detailed description has been given for clearness ofunderstanding only, and no unnecessary limitations should be understoodtherefrom, as modifications will be obvious to those skilled in the art.

What we claim is:
 1. A substantially rigid cuvette cartridge adapted foruse with chemical and microbiological analysis apparatus, said cartridgecomprising the following elements:a cartridge having a chamber with anopening for receiving fluid to be analyzed and a floor portion; aplurality of cuvettes in fluid communication with said chamber andextending in a given direction from said floor portion and having bafflemeans to direct the introduction of a liquid reagent; a first fluidpassage means extending in a direction opposite said given direction; asecond fluid passage means extending in said given direction said firstand second fluid passage means resulting in said fluid communicationbetween said chamber and cuvettes.
 2. A cuvette cartridge in accordancewith claim 1 wherein said first and second fluid passage means overlapforming an annular column between the external wall surface of firstfluid passage means and the internal wall surface of said second fluidpassage means.
 3. A cuvette cartridge in accordance with claim 1 whereinsaid chamber is positioned adjacently above said cuvettes.
 4. A cuvettecartridge in accordance with claim 2 wherein said first and secondpassage means are tubular shaped.
 5. A substantially rigid cuvettecartridge adapted for use with chemical and microbiological analysisapparatus, said cartridge comprising the following elements:a chamberhaving an opening for receiving fluid to be analyzed; a plurality ofcuvettes disposed beneath said chamber having baffle means to direct theintorduction of a liquid reagent, and paired concentric tubular members,the larger extending downward from the top of said chamber to a positionabove the bottom of said chamber and the smaller extending upward fromthe top of said cuvettes to a position below the top of said chamber,said concentric tubular members forming passageways between said chamberand cuvettes whereby pressure applied to the opening of said chamberwill cuase the fluid to be transferred from said chamber through thepassageways and into the cuvettes for analysis.